when it attempted to ascend, the effort was accomplished with difficulty.

The pectoral and abdominal fins were then removed from a second fish. It remained at the bottom of the vessel, and could not be made to ascend. Its progressive motion was not perceptibly more slow; but when the tail acted, the body showed a tendency to roll; and the single fins were widely expanded, as if to counteract this effect.

From a third fish the single fins were taken off, which produced a tendency to turn round, and the pectoral fins were kept constantly extended to obviate that motion.

From a fourth fish the pectoral and abdominal fins were cut off on one side, and it immediately lost the power of keeping its back upwards. The single fins were expanded; but the fish swam obliquely on its side, with the remaining pectoral and abdominal fins downwards.

From a fifth fish all the fins were removed. Its back was kept in a vertical position, whilst at rest, by the expansion of the tail; but it rolled half round at every attempt to move.

From a sixth fish the tail was cut off close to the body. Its progressive motion was considerably impeded, and the flexions of the spine were much increased during the endeavour to advance; but neither the pectoral nor abdominal fins seemed to be more actively employed.

From a seventh fish all the fins and the tail were removed. It remained almost without motion, floating near the surface of the water, with its belly upward.

These experiments were repeated on the roach, the gudgeon, and the minnow, with similar results.

The next observation relates to the velocity of fishes, which, being but little less than that of the flight of the swiftest birds, is very remarkable, considering the density of the medium in which they swim. And although the large proportion of muscles, and their advantageous application, may partly account for the phenomenon, yet the power would be inadequate to the effect, if it were not suddenly enforced, as is evident from the slow progress of eels, and such fishes as are incapable, from their length and flexibility, of giving a sudden lateral stroke.

The quickness and force of the action in the muscles of fishes are counterpoised by the short duration of their powers. The shortness of the muscular fibres, and the multiplied ramifications of the blood-vessels, are probably peculiar adaptations for the purpose of gaining velocity of action, which seems to be invariably connected with a very limited duration of it. Such

examples form an obvious contrast with the muscular structure of slow-moving animals, and with those partial arrangements where unusual continuance of action is concomitant.

On the Quantity and Velocity of the Solar Motion. By Dr. HERSCHEL. [1806.]

As the result of his several speculations, Dr. Herschel observes, that it appears, in the present state of our knowledge of the observed proper motions of the stars, we have reason to fix upon the quantity of the solar motion to be such as by an eye, placed at right angles to its direction, and at the distance of Sirius from us, would be seen to describe annually an arc of 1".116992 of a degree, and its velocity, till we are acquainted with the real distance of this star, can only be expressed by the proportional number 1,116,992.

:

The apparent velocities of Arcturus and Aldebaran, without a solar motion, were supposed, by a table already referred to, as 208 to 12; but when the deception arising from its parallactic effect is removed by calculation, these velocities are to each other only as 179 to 85, or as 2 to 1 and though Arcturus still remains a star that moves with great velocity, yet there are by the table four or five stars with nearly as much motion, and four with more. This solar motion also removes the deception by which the motion of a star of the consequence of a Orionis is so concealed as hardly to show any velocity; whereas, by computation, we find that it really moves at a rate which is fully equal to the motion of the sun.

The similarity of the directions of the sidereal motions is an indication that the stars, having such motions as well as the sun, are acted upon by some connecting cause, which can only be attraction; and as attraction will not explain the observed phenomena without the existence of projectile motions, it must be admitted that the motions of the stars are governed by the same two ruling principles which regulate the orbitual motions of the bodies of the solar system. It must also be admitted, that we may invert the inference from the operation of these causes in our system, and conclude that their influence upon the sidereal motions will tend to produce a similar effect; by which means the probable motion of the sun and of the stars in orbits becomes a subject that may receive the assistance of arguments supported by ob

servation,

Observations and Remarks on the Figure, Climate, and Atmosphere of Saturn and its Ring. By Dr. HERSCHEL. It is known that the axis of the planet's equator, as well as that of the ring, keeps its parallelism during the time of its revolution about the sun; and hence it follows, that the same change of situation, by which the ring is affected, must also produce similar alterations in the appearance of the planet: but since the shape of Saturn, though not strictly spherical, is very different from that of the ring, the changes occasioned by its aspects will be so minute that they only can expect to perceive them who have been accustomed to look at very small objects, and who are furnished with instruments that will show them distinctly, with a high and luminous magnifying

power.

In the year 1789, Dr. Herschel ascertained the proportion of the equatorial to the polar diameter of Saturn to be 22.81 to 20.61 in this measure was included the effect of the ring on the figure of the planet, though its influence had been investigated by direct observation. The rotation of the planet was determined afterwards by changes observed in the configuration of the belts.

The flattening at the poles of Saturn is more extensive than it is on the planet Jupiter. The curvature in high latitudes is also greater than on that planet. At the equator, on the contrary, the curvature is rather less than it is on Jupiter. Upon the whole, therefore, the shape of the globe of Saturn is not such as a rotatory motion alone could have given it.

From the latest observations it is inferred: 1. that the breadth of the ring is to the space between the ring and the planet, as about five to four. 2. The ring appears to be sloping towards the body of the planet, and the inside edge of it is probably of a spherical, or perhaps hyperbolical, form. 3. The shadow of the ring on the planet is broader on both sides than in the middle: this partly is a consequence of the curvature of the ring, which in the middle of its passage across the body hides more of the shadow in that place than at the sides. 4. The shadow of the body upon the ring is a little broader at the north than the south, so as not to be parallel with the outline of the body; nor is it so broad at the north as to become square with the direction of the ring. 5. The most northern dusky belt comes northwards on both sides as far as the middle of the breadth of the ring, where it passes behind the body. It is curved towards the south in the

middle.

Observations on the Camel's Stomach, respecting the Water it contains, and the Reservoirs in which that Fluid is enclosed. By Mr. EVERARD HOME.-[1807.]

THE camel, the subject of these observations, was a female brought from Arabia; it was 28 years old, and said to have been 20 years in England. It appears that the animal was worn out, and in a state of great debility, before it came into the hands of the college of surgeons, and in April last they put an end to its miseries, by means of a narrow doubleedged poniard, passed in between the skull and first vertebra of the neck: in this way the medulla oblongata was divided, and the animal instantaneously deprived of sensibility. "In the common mode of pithing an animal," says Mr. Home, "the medulla spinalis only is cut through, and the head remains alive, which renders it the most cruel mode of killing an animal that could be invented." The stomachs of this animal were the first things examined, and on measuring the capacities of these different reservoirs in the dead body, the anterior cells of the first stomach were found capable of containing one quart of water, when poured into them. The posterior cells three quarts. One of the largest cells held two ounces and a half, and the second stomach four quarts. This is much short of what those cavities can contain in the living animal, since there are large muscles covering the bottom of the cellular structure, to force out the water, which must have been contracted immediately after death, and by that means had diminished the cavities. By this examination it was proved, that the camel, when it drinks, conducts the water in a pure state into the second stomach, that part of it is retained there, and the rest runs over into the cellular structure of the first, acquiring a yellow colour.

The camel's stomach anteriorly forms one large bag, but when laid open, is found to be divided into two compartments on its posterior part, by a strong ridge, which passes down from the right side of the rifice of the oesophagus, in a longitudinal direction. On the left side of the termination of the œsophagus, a broad muscular band has its origin, from the coats of this first stomach, and passes down in the form of a solid parallel to the great ridge, till it enters the orifice of the second stomach. This band on one side, and the great ridge on the other, form a canal, which leads from the sophagus down to the cellular structure in the lower part of the first stomach. The orifice of the second stomach, when this muscle is not in action, is nearly shut, and at right angles

to the side of the first. Its cavity is a pendulous bag, with rows of cells, above which, between them and the muscle which passes along the upper part of the stomach, is a smooth surface extending from the orifice of this stomach to the termination in the third. Hence it is evident, that the second stomach neither receives the solid food in the first instance, as in the bullock, nor does it afterwards pass into its cavity or cellular structure. The food first passes into the general cavity of the first stomach, and that portion of it which lies in the recess immediately below the entrance of the œsophagus, under which the cells are situated, is kept moist, and is readily returned into the mouth, so that the cellular portion of the first stomach in the camel performs the same office as the second in the ruminants with horns. While the camel is drinking, the action of the muscular band opens the orifice of the second stomach, at the same time that it directs the water into it; and when the cells of that cavity are full, the rest runs off into the cellular structure of the first stomach immediately below, and afterwards into the general cavity: it seems that camels, when accustomed to go long journeys, in which they are kept without water, acquire the power of dilating the cells, so as to make them contain a more than ordinary quantity as a supply for their journey. When the cud has been chewed, it has to pass along the upper part of the second stomach before it can reach the third, which is thus managed: at the time that the cud is to pass from the mouth, the muscular band contracts with so much force, that it not only opens the orifice of the second stomach, but acting on the mouth of the third, brings it forwards into the second, by which means the muscular ridges that separate the rows of cells are brought close together, so as to exclude these cavities from the canal through which the cud passes. "It is this beautiful and very curious mechanism," says Mr. Home," which forms the peculiar character of the stomach of the camel, dromedary, and lama, fitting them to live in the sandy deserts where the supplies of water are so precarious.”

From the comparative view which Mr. Home has taken of the stomachs of the bullock and camel, it appears, that in the bullock there are three stomachs formed for the preparation of food, and one for digestion. In the camel, there is one stomach fitted to answer the purposes of two of the bullock; a second is employed as a reservoir for water, having nothing to do with the preparation of the food; a third is so small and simple in its structure, that it is not easy to ascertain its particular office.